Recently, with miniaturization of the data processing device including a central processing unit (CPU) configured on a semiconductor substrate, problems of a decrease of the breakdown voltage of transistors and an increase of the off-state leakage current have arisen.
Meanwhile, apparatuses using the data processing device are required to operate with an operating voltage, which is supplied to the data processing device, in a wide voltage range from a relatively high voltage (on the order of 5 V) to a relatively low voltage (3 V) and to a still lower voltage (1.8 V) in consideration of reduction of the power consumption, because of external factors (such as communication standards).
In order to operate in a wide voltage range, the data processing device has a plurality of power supply circuits (regulators) in the data processing device to generate an internal operating voltage from an externally supplied voltage and supply the generated voltage to internal functional blocks (see PTL 1), and determines the operation state of the power supply circuits in accordance with a signal based on the operation mode of the central processing unit (see PTL 2).
Also, in order to reduce the power consumption, the data processing device uses, as its internal voltage, a voltage generated by lowering an externally supplied voltage, and performs an intermittent operation in which a transition to a low power consumption state is made while operation is unnecessary. In the low power consumption state, the clock and the power supply voltage that are supplied to internal functional blocks of the data processing device are controlled. Specifically, the frequency of the clock to be supplied is lowered, the power supply voltage to be supplied is decreased, or supply of the clock and/or the power supply voltage is stopped (see PTL 3 and PTL 4).